Other currency than PLN

Scenario

When you are sending from a Polish company, you might need to issue the invoice in another currency than PLN. This can apply to:

invoices to customers outside Poland
Invoices to customers in Poland

In that case, information must be added:

The conversion rate PLN to the foreign currency
VAT amount expressed in 2 currencies:
- total VAT amount in the currency of the invoice
- total VAT amount in PLN

How to do with Billit API

The API content must contain the following elements:

Description	Billit API Field	KSeF field	Max. Length
Free description	Comments	Stopka / Informacje / StopkaFaktury	1000
Foreign Currency Conversion	FXRateToForeign	KursWaluty
Currency	Currency	Fa / KodWaluty

Example in Json and result in KSeF XML:

{
	"OrderNumber": "4098999",
	"Reference": "45123456789,
	"Currency": "EUR",
	"OrderDate": "2026-01-23",
	"ExpiryDate": "2026-01-30",
	"OrderType": "Invoice",
	"Comments": "Additional text info on header ",
  "OrderDirection": "Income",
	"FXRateToForeign": 4.2100,  //Conversion rate foreign currency
  "VentilationCode": "51",  // indicating the VAT codes when lines with 0 %.  See ventilation codes in documentation.
  "Customer": {
        "Name": "TESTCOMPANY BELGIUM ",
        "Addresses": [
            {
                "AddressType": "InvoiceAddress",
                "Name": "TESTCOMPANY POLSKA",
                "Street": "TESTSTREET",
                "StreetNumber": "14",
                "Zipcode": "9000",
                "City": "GENT",
                "CountryCode": "BE"
            }
        ],
        "VATNumber": "BE0570899999",
        "PartyType": "Customer",
        "VATLiable": true,
        "Language": "EN",
        "VATDeductable": true
},
	"OrderLines": [
		{
			"Quantity": 1.0,
			"UnitPriceExcl": 1.00,
			"Description": "test", 
			"VATPercentage": 23.00
		},
	]
}

<Faktura xmlns:etd="http://crd.gov.pl/xml/schematy/dziedzinowe/mf/2022/01/05/eD/DefinicjeTypy/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://crd.gov.pl/wzor/2025/06/25/13775/">
 <Fa>
   <KodWaluty>EUR</KodWaluty> //foreign currency 
   <P_1>2026-02-25</P_1> // invoice date 
   <P_2>test8</P_2> //invoice number 
   <P_6>2026-02-25</P_6> // date of supply 
   <P_13_1>10.00</P_13_1> // taxable base in currency of the invoice 
   <P_14_1>2.30</P_14_1> //   VAT amount derived from P13_1 base amount in Euro
   <P_14_1W>9.68</P_14_1W>   //  VAT amount equivalent in PLN (calculated by Billit based on exchange rate) 
   <P_15>12.30</P_15> // total amount including VAT (currency of the invoice) 
   <KursWalutyZ>4.21000</KursWalutyZ>  // > foreign conversion rate used
 </Fa>
</Faktura>